Discerning short- and long-range charge orders in YBa₂Cu₃O_6+x using ultrafast resonant soft X-ray scattering

Time-resolved resonant soft X-ray scattering is emerging as a key technique for studying the interplay between order parameters in complex materials. Recent studies have shown a strong dynamical interaction between superconductivity and charge density waves (CDW) in cuprates. However, the photo-induced CDW dynamics in the non-superconducting state remain poorly understood. Here we present an ultrafast soft x-ray scattering study of the CDW dynamics in YBa₂Cu₃O_6+x. The fluence-dependent response of the CDW peak shows clear saturation above a critical fluence Φ_C, indicating complete quenching of the long-range order. Surprisingly, momentum scans reveal a persistent broad residual peak above Φ_C. We compare this residual peak to the CDW signature well above the transition temperature and analyze the temporal evolution of the CDW momentum profile to understand the nature of these short-range correlations.